Participation in social networking sites offers many potential benefits for university students. Online interaction on these sites provides various opportunities for them to learn and improve self-control, tolerate and respect the viewpoints of others, express emotions in healthy and orderly ways, and think and make decisions critically. These sites also provide them with a virtual space to execute time, form close connections with friends without being spatially restricted and provide space for young people’s self-development. However, the number of studies examining university students’ social networking sites, media literacy, and critical thinking is very limited in the literature. Therefore, this research examined the effects of motivation to use social networking sites on students’ media literacy and critical thinking. The research also examined the relationships between students’ motivation for using social networks, media literacy, and critical thinking. The data were collected using three data collection instruments. The participants were 211 university students enrolled at two universities in Bangkok, Thailand. The results showed significant positive correlations between motivation to use social networking sites, and critical thinking, that university students with better performance in information and learning show better performance in critical thinking and reflection skills. The results also showed remarkable positive correlations between motivation for using social networking sites and media literacy, indicating that university students with better performance in information and learning show better performance in multimedia messages and multimedia organization and analysis. In addition, the results also revealed positive correlations between critical thinking and media literacy. The implications are made based on the results obtained from this research.